Joint Power and Feedback Design for Multi-Antenna NOMA Systems with Limited Feedback

This paper proposes a multiple-antenna non-orthogonal multiple access scheme including channel state information (CSI) quantization and feedback, user clustering, signal superposition coding, transmit beamforming, and successive interference cancellation at receivers under a general limited CSI feedback framework for frequency duplex division systems. Given a combination of system parameters, we conduct a mathematically strict performance analysis of the considered system, and obtain a closed-form lower bound on the ergodic rate of each user without assuming any extreme for system parameters, which has never been obtained before. Then, we jointly optimize two key parameters, i.e., transmit power and the number of feedback bits allocated to each user, and propose low-complexity closed-form solutions. Finally, numerical results are presented to verify our theoretical results and to illustrate the advantages in accuracy and performance over some existing related results under practical conditions.